Radiation exposure by digital radiographic imaging in very low birth weight infants.

OBJECTIVE: The aim of this study was to determine the cumulative effective doses (CED) from digital radiographic imaging in very low birth weight infants treated in a tertiary care neonatal intensive care unit (NICU). STUDY DESIGN: The CED for each infant was retrospectively calculated using a voxel-based model. The results were compared with previous studies applying conventional radiography. RESULTS: Two hundred and six preterm infants were included into this study. Neonates received a median of four radiographs (range: 1-68) and a CED of 50 µSv (4-883 µSv). Overall mean CED was lower than in previously published data applying conventional radiography. Factors contributing to a lower radiation dose per infant in our study were a lower number of radiographs and smaller field sizes per radiographic image. CONCLUSIONS: The number of conducted radiographs per patient and the employed field size had a higher impact on the CED than the applied radiographic technology.

Analysis of the influence of imaging-related uncertainties on cerebral aneurysm deformation quantification using a no-deformation physical flow phantom.

Cardiac-cycle related pulsatile aneurysm motion and deformation is assumed to provide valuable information for assessing cerebral aneurysm rupture risk. Accordingly, numerous studies addressed quantification of cerebral aneurysm wall motion and deformation. Most of them utilized in vivo imaging data, but image-based aneurysm deformation quantification is subject to pronounced uncertainties: unknown ground-truth deformation; image resolution in the order of the expected deformation; direct interplay between contrast agent inflow and image intensity. To analyze the impact of the uncertainties on deformation quantification, a multi-imaging modality ground-truth phantom study is performed. A physical flow phantom was designed that allowed simulating pulsatile flow through a variety of modeled cerebral vascular structures. The phantom was imaged using different modalities [MRI, CT, 3D-RA] and mimicking physiologically realistic flow conditions. Resulting image data was analyzed by an established registration-based approach for automated wall motion quantification. The data reveals severe dependency between contrast media inflow-related image intensity changes and the extent of estimated wall deformation. The study illustrates that imaging-related uncertainties affect the accuracy of cerebral aneurysm deformation quantification, suggesting that in vivo imaging studies have to be accompanied by ground-truth phantom experiments to foster data interpretation and to prove plausibility of the applied image analysis algorithms.